Bugaboo Bee+ Any good off road? Need a carrycot?

Hello, I'm thinking about getting a Bugaboo Bee+ but am not sure if it will be up to occasional walks across a grassy park and off-road dog walking.

Also, for a newborn is it better to have a flat bassinet/carrycot? Although the Bee says its suitable for newborn it doesn't lie 100% horizontal and I don't think it has a detachable carrycot. Is it better to get a detachable carrycot for a newborn?